The present invention is related to optical fiber networks, and, in particular, to switches for directing optical signals along fibers of an optical network, or to attenuators for controlling the strength of optical signals in an optical fiber.
In optical fiber networks, switches are often used to direct optical signals along one optical fiber or another. Many, if not most, of these switches are electromechanical devices which have parts moving in response to electrical signals. While miniaturization has desirably reduced the switching speeds of such devices, switch parts are still being accelerated and decelerated with the consequent wear and breakdown. Furthermore, the physical movement of parts places an effective limitation on further improvement on switching speeds. Hence it is desirable that fiberoptic devices, including switches, be purely optical, or electro-optical, devices. Such devices ideally do not have moving parts.
The present invention provides for a switch which is electro-optical. By applying preselected electrical voltages to the switch corresponding to an On state and an Off state, the switch transmits optical signals between two optical fibers or blocks the signals. Furthermore, by applying electrical voltages intermediate the preselected voltages, the switch operates as an electro-optical attenuator. Attenuators are often used in fiberoptic networks to balance the strength of optical signals along different paths. By controlling the voltage to the device of the present invention, the strength of the signals between two optical fibers is modulated.